Biochemical events associated with transformation due to expression of viral oncogenes in NIH/3T3 cells were studied. Expression of v-ras and its product, p21 were associated with reduction or suppression of synthesis of a number of cellular proteins. Revertant lines which still expressed v-ras and p21 but were not transformed showed restoration of synthesis of most, but not all of these proteins. Two proteins were of special interest - p37/pI-4.8 and p41/pI-4.8. Synthesis of these proteins was strongly suppressed not only by v-ras, but by all of the 5 other oncogenes examined, regardless of relation to v-ras. These findings suggest that a final common pathway for oncogenesis by many oncogenes involves suppression of synthesis of p37/4.8 and p41/4.8, and that normal levels of synthesis of these proteins is essential for maintenance of the normal growth pattern in 3T3 cells.